A291847 - OEIS

%I #9 Sep 03 2017 16:58:43

%S 1,4,26,224,2389,30324,446109,7460928,139775763,2899264620,

%T 65954625560,1632654953280,43688087178059,1256602120453484,

%U 38661480001233486,1266934683224418816,44054989554206606603,1620147926716343851500,62826169539072988352134,2562071016044926371845920,109611597248567432265872903,4908887251696851858305862332

%N A diagonal of irregular triangle A291845.

%C G.f. of row n in triangle A291845 equals Product_{k=0..n-1} (1 + (2*k+1)*x + x^2), with row sums equal to the odd double factorials A001147.

%H Paul D. Hanna, <a href="/A291847/b291847.txt">Table of n, a(n) for n = 0..300</a>

%F a(n) = A291845(n+1,n).

%o (PARI) /* As a Diagonal in Triangle A291845 */

%o {A291845(n, k)=polcoeff(prod(j=0, n-1, 1 + (2*j+1)*x + x^2), k)}

%o {for(n=0,25,print1(A291845(n+1,n),", "))}

%Y Cf. A291845, A291846, A291848.

%K nonn

%O 0,2

%A _Paul D. Hanna_, Sep 03 2017